4 editcap - Edit and/or translate the format of capture files
9 S<[ B<-c> E<lt>packets per fileE<gt> ]>
10 S<[ B<-C> E<lt>choplenE<gt> ]>
12 S<[ B<-E> E<lt>error probabilityE<gt> ]>
13 S<[ B<-F> E<lt>file formatE<gt> ]>
14 S<[ B<-A> E<lt>start timeE<gt> ]>
15 S<[ B<-B> E<lt>stop timeE<gt> ]>
18 S<[ B<-s> E<lt>snaplenE<gt> ]>
19 S<[ B<-t> E<lt>time adjustmentE<gt> ]>
20 S<[ B<-T> E<lt>encapsulation typeE<gt> ]>
24 S<[ I<packet#>[-I<packet#>] ... ]>
28 B<Editcap> is a program that reads some or all of the captured packets from the
29 I<infile>, optionally converts them in various ways and writes the
30 resulting packets to the capture I<outfile> (or outfiles).
32 By default, it reads all packets from the I<infile> and writes them to the
33 I<outfile> in libpcap file format.
35 A list of packet numbers can be specified on the command line; ranges of
36 packet numbers can be specified as I<start>-I<end>, referring to all packets
37 from I<start> to I<end>.
38 The selected packets with those numbers will I<not> be written to the
40 If the B<-r> flag is specified, the whole packet selection is reversed;
41 in that case I<only> the selected packets will be written to the capture file.
43 B<Editcap> is able to detect, read and write the same capture files that
44 are supported by B<Wireshark>.
45 The input file doesn't need a specific filename extension; the file
46 format and an optional gzip compression will be automatically detected.
47 Near the beginning of the DESCRIPTION section of wireshark(1) or
48 L<http://www.wireshark.org/docs/man-pages/wireshark.html>
49 is a detailed description of the way B<Wireshark> handles this, which is
50 the same way B<Editcap> handles this.
52 B<Editcap> can write the file in several output formats. The B<-F>
53 flag can be used to specify the format in which to write the capture
54 file, B<editcap -F> provides a list of the available output formats.
60 =item -c E<lt>packets per fileE<gt>
62 Sets the maximum number of packets per output file. Each output file will
63 be created with a suffix -nnnnn, starting with 00000. If the specified
64 number of packets are written to the output file, the next output file is
65 opened. The default is to use a single output file.
67 =item -C E<lt>choplenE<gt>
69 Sets the chop length to use when writing the packet data.
70 Each packet is chopped at the packet end by a few <choplen> bytes of data.
72 This is useful in the rare case that the conversion between two file
73 formats leaves some random bytes at the end of each packet.
77 Attempts to remove duplicate packets. The length and MD5 sum of the
78 current packet are compared to the previous four packets. If a match
79 is found, the packet is skipped.
81 =item -E E<lt>error probabilityE<gt>
83 Sets the probabilty that bytes in the output file are randomly changed.
84 B<Editcap> uses that probability (between 0.0 and 1.0 inclusive)
85 to apply errors to each data byte in the file. For instance, a
86 probability of 0.02 means that each byte has a 2% chance of having an error.
88 This option is meant to be used for fuzz-testing protocol dissectors.
90 =item -F E<lt>file formatE<gt>
92 Sets the file format of the output capture file.
93 B<Editcap> can write the file in several formats, B<editcap -F>
94 provides a list of the available output formats. The default
95 is the B<libpcap> format.
97 =item -A E<lt>start timeE<gt>
99 Saves only the packets whose timestamp is on or after start time.
100 The time is given in the following format YYYY-MM-DD HH:MM:SS
102 =item -B E<lt>stop timeE<gt>
104 Saves only the packets whose timestamp is on or before stop time.
105 The time is given in the following format YYYY-MM-DD HH:MM:SS
109 Prints the version and options and exits.
113 Reverse the packet selection.
114 Causes the packets whose packet numbers are specified on the command
115 line to be written to the output capture file, instead of discarding them.
117 =item -s E<lt>snaplenE<gt>
119 Sets the snapshot length to use when writing the data.
120 If the B<-s> flag is used to specify a snapshot length, packets in the
121 input file with more captured data than the specified snapshot length
122 will have only the amount of data specified by the snapshot length
123 written to the output file.
125 This may be useful if the program that is
126 to read the output file cannot handle packets larger than a certain size
127 (for example, the versions of snoop in Solaris 2.5.1 and Solaris 2.6
128 appear to reject Ethernet packets larger than the standard Ethernet MTU,
129 making them incapable of handling gigabit Ethernet captures if jumbo
132 =item -t E<lt>time adjustmentE<gt>
134 Sets the time adjustment to use on selected packets.
135 If the B<-t> flag is used to specify a time adjustment, the specified
136 adjustment will be applied to all selected packets in the capture file.
137 The adjustment is specified as [-]I<seconds>[I<.fractional seconds>].
138 For example, B<-t> 3600 advances the timestamp on selected packets by one
139 hour while B<-t> -0.5 reduces the timestamp on selected packets by
142 This feature is useful when synchronizing dumps
143 collected on different machines where the time difference between the
144 two machines is known or can be estimated.
146 =item -T E<lt>encapsulation typeE<gt>
148 Sets the packet encapsulation type of the output capture file.
149 If the B<-T> flag is used to specify an encapsulation type, the
150 encapsulation type of the output capture file will be forced to the
152 B<editcap -T> provides a list of the available types. The default
153 type is the one appropriate to the encapsulation type of the input
157 forces the encapsulation type of the output file to be the specified
158 type; the packet headers of the packets will not be translated from the
159 encapsulation type of the input capture file to the specified
160 encapsulation type (for example, it will not translate an Ethernet
161 capture to an FDDI capture if an Ethernet capture is read and 'B<-T
162 fddi>' is specified). If you need to remove/add headers from/to a
163 packet, you will need od(1)/text2pcap(1).
167 Causes B<editcap> to print verbose messages while it's working.
173 To see more detailed description of the options use:
177 To shrink the capture file by truncating the packets at 64 bytes and writing it as Sun snoop file use:
179 editcap -s 64 -F snoop capture.pcap shortcapture.snoop
181 To delete packet 1000 from the capture file use:
183 editcap capture.pcap sans1000.pcap 1000
185 To limit a capture file to packets from number 200 to 750 (inclusive) use:
187 editcap -r capture.pcap small.pcap 200-750
189 To get all packets from number 1-500 (inclusive) use:
191 editcap -r capture.pcap 500.pcap 1-500
195 editcap capture.pcap 500.pcap 501-9999999
197 To filter out packets 10 to 20 and 30 to 40 into a new file use:
199 editcap capture.pcap selection.pcap 10-20 30-40
201 To introduce 5% random errors in a capture file use:
205 editcap -E 0.05 capture.pcap capture_error.pcap
211 tcpdump(8), pcap(3), wireshark(1), mergecap(1), text2pcap(1), od(1)
215 B<Editcap> is part of the B<Wireshark> distribution. The latest version
216 of B<Wireshark> can be found at L<http://www.wireshark.org>.
218 HTML versions of the Wireshark project man pages are available at:
219 L<http://www.wireshark.org/docs/man-pages>.
225 Richard Sharpe <sharpe[AT]ns.aus.com>
230 Guy Harris <guy[AT]alum.mit.edu>
231 Ulf Lamping <ulf.lamping[AT]web.de>